Oscar Benjamin <oscar.j.benja...@gmail.com>: > The mass is carried by the new particles. The new particles may have a > total *rest mass* which differs from the total rest mass of the > previous particles. However the total mass is the rest mass plus the > mass associated with the "kinetic energy" of the particles. > > [...] > > Mass and energy are not interchangeable in the sense that you can > exchange one for the other with e=mc^2 giving the exchange rate. > Rather mass and energy are *the same thing*. Although they are > different concepts defined in different ways and having different > dimensions and units they are inseparable: e=mc^2 gives us the > proportion in which the two appear together.
A physicist mentioned to me that the word "mass" has replaced the term "rest mass" in modern Physics lingo. That's why you say a photon is "massless" even though every observable photon has a relativistic mass. It's all in the terminology. As for the existence of a negative mass, it is interesting to note that the (rest) mass of an alpha particle is less than the sum of the (rest) masses of its constituents. About 1% of the mass is "missing." Marko -- https://mail.python.org/mailman/listinfo/python-list
